In September of 1950 Tung-Sol introduced the 5881, an uprated and industrial version of the 6L6GA with a 23.5 watt plate dissipation, opening the doors to the hi-fi movement of the 1950s. This rugged tube also found a home in the '59 Fender Bassman and servo amplifiers used in B-52 bombers. In 1955 Tung-Sol raised the bar of high fidelity with the introduction of the 35 watt 6550, which could deliver 100 watts with a pair in push-pull configuration. This tube was used in the Dynaco Mark III and Sunn amplifers.
Now the factory in Saratov announces the Tung-Sol KT120, which has a plate dissipation of 60 watts, making it the most powerful tube in the 6550/KT88/KT90 family. A pair of these tubes in push-pull configuration can deliver power levels of 150 or more watts. When used at the parameters found in existing 6550/KT88/KT90 circuits, the Tung-Sol KT120 is impervious to overload, delivering peak power with extreme reliability and long tube life. However, taking advantage of the higher current handling capacity of these tubes, a very unique and super powerful and stable amp can be designed using the Tung-Sol KT-120.
These tubes can totally transform your system, they are that good ! They draw up to an additional (0.3 amps= 300 miliamps) of heater current as compared to a standard KT88 or 6550. This will not be a problem in most amps. We do not recommend biasing them any higher than your manufacturer recommends so as not to overheat your power transformer. In my own amp, my max setting is (44.0 miliamps) and I do not exceed that bias setting. THE SONIC SUPERIORITY of these tubes is like enjoying all the best qualities of a single-ended triode amp, but with the punch, power and dynamics of a really great push pull amplifier! You get the incredible transparency and liquidity and clarity of a 300B but with a big set of balls!
These are supplied as closely matched pairs, burned in for 24 hrs.,tested in an amp.